Fix handling of Top Level Operation Headers

Author: cortinico

plugin/src/main/java/com/yelp/codegen/KotlinGenerator.kt

@@ -28,7 +28,11 @@ class KotlinGenerator : SharedCodegen() {
          * This number represents the version of the kotlin template
          * Please note that is independent from the Plugin version
          */
-        @JvmStatic val VERSION = 11
+        @JvmStatic val VERSION = 12
+
+        // Vendor Extension use to generate the list of top level headers
+        const val HAS_OPERATION_HEADERS = "hasOperationHeaders"
+        const val OPERATION_HEADERS = "operationHeaders"
     }
 
     private val apiDocPath = "docs/"
@@ -404,7 +408,6 @@ class KotlinGenerator : SharedCodegen() {
 
         codegenOperation.imports.add("retrofit2.http.Headers")
         codegenOperation.vendorExtensions[X_OPERATION_ID] = operation?.operationId
-
         getHeadersToIgnore().forEach { headerName ->
             ignoreHeaderParameter(headerName, codegenOperation)
         }
@@ -413,6 +416,7 @@ class KotlinGenerator : SharedCodegen() {
         if (!basePath.isNullOrBlank()) {
             codegenOperation.path = codegenOperation.path.removePrefix("/")
         }
+        processTopLevelHeaders(codegenOperation)
         return codegenOperation
     }
 
@@ -451,4 +455,30 @@ class KotlinGenerator : SharedCodegen() {
     override fun removeNonNameElementToCamelCase(name: String?): String {
         return super.removeNonNameElementToCamelCase(name, "[-_:;#\\[\\]]")
     }
+
+    /**
+     *  Function to check if there are Headers that should be applied at the Top level on Retrofit
+     *  with the @Headers annotation. This method will populate the `hasOperationHeaders` and `operationHeaders`
+     *  vendor extensions to support the mustache template.
+     */
+    internal fun processTopLevelHeaders(operation: CodegenOperation) {
+        val topLevelHeaders = mutableListOf<Pair<String, String>>()
+
+        // Send the X-Operation-Id header only if a custom operation ID was set.
+        val operationId = operation.vendorExtensions[X_OPERATION_ID] as String?
+        if (!operationId.isNullOrBlank()) {
+            topLevelHeaders.add(HEADER_X_OPERATION_ID to operationId)
+        }
+
+        // Send the Content-Type header for the first `consume` mediaType specified.
+        val firstContentType = operation.consumes?.firstOrNull()
+        if (operation.formParams.isNullOrEmpty() && firstContentType != null) {
+            firstContentType["mediaType"]?.let {
+                topLevelHeaders.add(HEADER_CONTENT_TYPE to it)
+            }
+        }
+
+        operation.vendorExtensions[HAS_OPERATION_HEADERS] = topLevelHeaders.isNotEmpty()
+        operation.vendorExtensions[OPERATION_HEADERS] = topLevelHeaders
+    }
 }

plugin/src/main/java/com/yelp/codegen/SharedCodegen.kt

@@ -32,11 +32,16 @@ const val ARTIFACT_ID = "artifact_id"
 const val GROUP_ID = "group_id"
 const val HEADERS_TO_IGNORE = "headers_to_ignore"
 
+// Vendor Extensions Names
 internal const val X_NULLABLE = "x-nullable"
 internal const val X_MODEL = "x-model"
 internal const val X_OPERATION_ID = "x-operation-id"
 internal const val X_UNSAFE_OPERATION = "x-unsafe-operation"
 
+// Headers Names
+internal const val HEADER_X_OPERATION_ID = "X-Operation-Id"
+internal const val HEADER_CONTENT_TYPE = "Content-Type"
+
 abstract class SharedCodegen : DefaultCodegen(), CodegenConfig {
 
     // Reference to the Swagger Specs

plugin/src/main/resources/kotlin/retrofit2/api.mustache

@@ -25,19 +25,12 @@ interface {{classname}} {
   {{#isMultipart}}@retrofit2.http.Multipart{{/isMultipart}}{{^isMultipart}}@retrofit2.http.FormUrlEncoded{{/isMultipart}}
   {{/-first}}
   {{/formParams}}
-  {{^formParams}}
-  {{#prioritizedContentTypes}}
-  {{#-first}}
-  @Headers({
-    "Content-Type:{{{mediaType}}}"
-  })
-  {{/-first}}
-  {{/prioritizedContentTypes}}
-  {{/formParams}}
-  @Headers({{#vendorExtensions.x-operation-id}}{{{newline}}}    "X-Operation-ID: {{vendorExtensions.x-operation-id}}"{{/vendorExtensions.x-operation-id}}{{^formParams}}{{#prioritizedContentTypes}}{{#-first}},
-    "Content-Type:{{{mediaType}}}"{{/-first}}{{/prioritizedContentTypes}}{{/formParams}}
-  )
-
+  {{#vendorExtensions.hasOperationHeaders}}
+  @Headers(
+    {{#vendorExtensions.operationHeaders}}"{{first}}: {{second}}"{{^-last}},
+    {{/-last}}{{#-last}}
+  ){{/-last}}{{/vendorExtensions.operationHeaders}}
+  {{/vendorExtensions.hasOperationHeaders}}
   @{{httpMethod}}("{{{path}}}"){{#vendorExtensions.x-unsafe-operation}}{{#isDeprecated}}
       @Deprecated(message = "Deprecated and unsafe to use"){{/isDeprecated}}{{^isDeprecated}}
       @Deprecated(message = "Unsafe to use"){{/isDeprecated}}

plugin/src/test/java/com/yelp/codegen/KotlinGeneratorTest.kt

@@ -1,6 +1,7 @@
 package com.yelp.codegen
 
 import io.swagger.codegen.CodegenModel
+import io.swagger.codegen.CodegenOperation
 import io.swagger.codegen.CodegenProperty
 import io.swagger.models.Info
 import io.swagger.models.Operation
@@ -353,4 +354,14 @@ class KotlinGeneratorTest {
         assertEquals("42.0.0", swagger.info.version)
         assertEquals("/v2", generator.basePath)
     }
+
+    @Test
+    fun processTopLevelHeaders_withNoHeaders() {
+        val generator = KotlinGenerator()
+        val operation = CodegenOperation()
+
+        generator.processTopLevelHeaders(operation)
+
+        assertEquals(false, operation.vendorExtensions["hasOperationHeaders"])
+    }
 }